Protein hydrolysate formula maintains homeostasis of plasma amino acids in preterm infants.

BACKGROUND: Plasma amino acid concentrations were measured in preterm infants who were fed either a new hydrolyzed cow's milk protein formula or a standard preterm infant formula. It was hypothesized that feeding with the hydrolysate results in preprandial amino acid concentrations that are significantly different from the concentrations found when feeding with the standard formula. METHODS: Fifteen preterm infants, median gestational age, 29 weeks (range, 24-32 weeks); birth weight, 1241 g (range, 660-1900 g); and postnatal age, 18 days (range, 7-54 days) receiving full enteral feedings (>150 ml/kg x day), were enrolled. The intervention was randomized allocation to the formula with hydrolyzed or natural cow's milk protein (the whey/casein ratio was 60:40 in both formulas). In a crossover design, each formula was fed for 5 days, and plasma amino acids were analyzed on day 4 or 5 of each 5-day period. RESULTS: In spite of the 12% higher amino acid intake with hydrolysate formula, the median individual plasma amino acid concentrations were virtually identical with both formulas, and they were within the 10th and the 90th percentile of the reference of levels in the umbilical cord artery after elective cesarean delivery or of breast-fed newborn infants. The median concentrations of lysine and aspartic acid were higher with hydrolyzed formula feeding (p<0.05; two-tailed Mann-Whitney test). With both formulas, single amino acid concentrations were out of the reference values. CONCLUSION: Virtually identical plasma amino acid concentration patterns were measured with the new hydrolyzed preterm infant formula and the standard preterm infant formula, but longitudinal studies are required before the studied protein hydrolysate can be recommended for preterm feeding in general.     

Higher urinary excretion of essential amino acids in preterm infants fed protein hydrolysates

Aim: Protein hydrolysates have been introduced in preterm formulae, but it is not clear whether they are needed for the feeding of preterm infants. We designed a randomized, controlled trial to test the effects of a preterm formula with hydrolysed cow's milk proteins on short-term growth and urinary and plasma amino acids levels. Methods: Infants with a birthweight ≤1750 g and gestational age ≤34 wk fed a conventional preterm infant formula (formula B) or a hydrolysed formula (formula A). Weight was measured daily; length, head circumference, mid-arm circumference and total skinfold thickness were measured weekly. Blood and urine were analysed for amino acid concentrations at start, 14 and 28 d. Results: Twenty-one infants met the criteria for randomization. The daily feeding volumes were: formula A 172.8±5.6 vs formula B 170.1±2.8 ml/kg/d. Infants fed with formula A showed slower weight gain (17.4±3.4 vs 20.5±3.3 g/kg/d; p=0.045) and lower mean change in Z-scores for weight (-0.18±0.16 vs 0.00±0.09; p=0.009) and for head circumference (-0.06±0.13 vs 0.06±0.13; p=0.049). After 14 d, infants receiving formula A had statistically significant higher urinary levels of essential amino acids compared to infants receiving formula B.

Conclusion: Our results support the hypothesis of less nutritional value of hydrolysed versus conventional preterm formulae. Higher renal excretion of essential amino acids may be one of the mechanisms involved. These findings must be confirmed by further studies with larger sample sizes and protein hydrolysates with different degrees of hydrolysis.     

The effect of birth asphyxia on plasma free amino acids in preterm newborn infants

The postnatal plasma amino acid pattern was compared in 16 asphyxiated and 13 non-asphyxiated preterm newborn infants. The lactic acidosis induced by asphyxia was associated with a marked rise in the total amino acid content of the plasma. Among the 17 individual amino acids determined the concentrations of alanine, proline, taurine, glutamate, valine, methionine and lysine were significantly elevated. The accumulation of alanine was particulary marked and its concentration showed a significant linear correlation with that of lactate (p less 0.001). A similar relationship was observed between other potentially glucogenic amino acids and lactate. It is suggested that an impaired gluconeogenesis may be responsible for the accumulation of glucogenic amino acids. The response of the plasma aminogram to asphyxia resembles that associated with hypoglycaemia in the small-for-gestational-age infant, where a delay in the maturation of key gluconeogenic enzymes seems to account for the reduced hepatic disposal of glucose precursors.     

Effect of hypothermia on plasma metabolites in preterm newborn infants with particular references to plasma free amino acids.

Blood glucose, blood lactate, plasma free fatty acids, plasma alpha-amino nitrogen, plasma free amino acids and blood urea nitrogen were measured in 15 hypothermic preterm infants (mean rectal temperature: 34.5 +/- 0.28 degrees C) during a 2-hour 'warming-up' period following admission to our neonatal intensive care unit. Hypothermia was associated with lactacidemia and hyperalaninemia. The increase in body temperature of the infants resulted in the decrease of lactacidemia and hyperalaninemia. Normal levels of other metabolites remained unchanged.     

The influence of dietary nucleotides on erythrocyte membrane fatty acids and plasma lipids in preterm infants

Objective : The objective of this study was to evaluate whether a regular formula for premature infants supplemented with nucleotides has any influence on plasma lipids and erythrocyte membrane fatty acids. Methods : Preterm infants fed either human milk supplemented with human milk protein (HM, n = 14), nucleotide-supplemented preterm formula (NF, n = 13), or a regular preterm formula (F, n = 13) were included in the study. The NF was supplemented with 18.2 mg cytidine monophosphate/1 (CMP), 7.0 mg uridine monophosphate/1 (UMP), 6.4mg adenosine monophosphate/1 (AMP), 3.0mg inosine monophosphate/1 (IMP) and 3.0 mg guanosine monophosphate/1 (GMP). Results : There were significantly higher concentrations of triglycerides (TG) in infants fed NF compared to those fed F (191.42 ± 79.58 vs 108.21 ± 43.73, p < 0.001, mean ± SD lipid concentrations, mg/100ml plasma). Infants fed F had significantly lower concentrations of total cholesterol (94.34 ± 11.71 vs 115.69 ± 39.29, p < 0.01) and TG in plasma (108.21 ± 43.73 vs 172.27 ± 68.19, p < 0.001, mean ± SD lipid concentrations, mg/100ml plasma) when compared to HM-fed infants. There were no significant differences in any of the erythrocyte membrane fatty acids and total long-chain polyunsaturated fatty acids (LC-PUFA) between NF and F during the study period (6 weeks). Furthermore, total LC-PUFA and docosahexaenoic acid (DHA) concentrations in red blood cell were not significantly different when infants fed NF were compared to those fed HM. In contrast, however, infants fed F had significantly lower concentrations of total n-3 LC-PUFA ( p < 0.01) and DHA ( p < 0.01) than those found in HM-fed infants. Conclusions : These results do not suggest an effect of nucleotides on the red blood cell LC-PUFA profile in preterm infants. However, the nucleotides may increase the concentrations of triglycerides in plasma.     

Early infusion of high-dose amino acids to improve nitrogen balance in preterm infants

目的 评价早期输注大剂量氨基酸对改善早产儿氮平衡的有效性.方法 将2010年1月-2010年12月间出生24 h内体质量1000～2000 g入住新生儿重症监护室(NICU)接受肠道外营养治疗的早产儿,随机分为两组.实验组于生后24 h内输注氨基酸2.0 g/(kg·d)起.每天增加0.85 s/ks.预期峰值3.7 g/(kg·d);对照组于出生24 h内输注氨基酸0.5g/(kg·d)起,每天增加0.5 g/ks,预期峰值3.7 g/(kg·d).结果 实验组早产儿生后第1周均处于正氮平衡;对照组早产儿生后前3 d均处于负氮平衡;实验组早产儿第1周每天平均氮平衡值均大于对照组,差异有统计学意义(P均<0.01).实验组早产儿体质量下降百分比少于对照组,差异有统计学意义(P<0.05);头围增长大于对照组,差异有统计学意义(P<0.05);达到肠内营养418.4 kJ/kg的天数、恢复出生体质量的天数和体质量达到2 000 g的天数均少于对照组,差异有统计学意义(P均<0.05).结论 早产儿生后24 h内即开始输注大剂量氨基酸(2.0 g/kg)能显著改善氮平衡,增加喂养耐受性和促进早产儿生长.     

早期输注大剂量氨基酸对改善早产儿氮平衡的有效性研究

目的评价早期输注大剂量氨基酸对改善早产儿氮平衡的有效性。方法将2010年1月—2010年12月间出生24 h内体质量1 000～2 000 g入住新生儿重症监护室(NICU)接受肠道外营养治疗的早产儿,随机分为两组。实验组于生后24 h内输注氨基酸2.0 g/(kg.d)起,每天增加0.85 g/kg,预期峰值3.7 g/(kg.d);对照组于出生24 h内输注氨基酸0.5 g/(kg.d)起,每天增加0.5 g/kg,预期峰值3.7 g/(kg.d)。结果实验组早产儿生后第1周均处于正氮平衡;对照组早产儿生后前3 d均处于负氮平衡;实验组早产儿第1周每天平均氮平衡值均大于对照组,差异有统计学意义(P均<0.01)。实验组早产儿体质量下降百分比少于对照组,差异有统计学意义(P<0.05);头围增长大于对照组,差异有统计学意义(P<0.05);达到肠内营养418.4 kJ/kg的天数、恢复出生体质量的天数和体质量达到2 000 g的天数均少于对照组,差异有统计学意义(P均<0.05)。结论早产儿生后24 h内即开始输注大剂量氨基酸(2.0 g/kg)能显著改善氮平衡,增加喂养耐受性和促进早产儿生长。     

早期大剂量氨基酸在早产儿静脉营养中的研究进展

随着早产儿存活率的日益提高,其日后的营养状况逐渐被关注.特别是极低和超低出生体重儿,由于宫内营养不足,出生后对热卡需求高,单纯经胃肠道喂养往往不能满足其营养和代谢需求,静脉营养是其获取能量的重要方法.近年来,国外已普遍开展了静脉大剂量氨基酸的早期应用,并发现该方法不仅安全,而且对改善早产儿生长和营养状况是有效的.因此,生后迅速建立营养支持对追赶生长是十分必要的.     

Human milk protein and medium-chain triglyceride oil supplementation of human milk: plasma amino acids in very low-birth-weight infants

Fifty-one very low-birth-weight infants (birth weight less than 1,520 g) randomly fed either human milk or human milk supplemented with human milk protein and/or with medium-chain triglyceride (MCT) oil were observed. Plasma amino acids from these infants were studied at 2, 8, and 10 weeks. Medium-chain triglyceride oil supplementation had minimal or no influence on plasma amino acids. Human milk protein supplementation resulted in increased concentrations of all amino acids at all ages studied. The concentrations were 1.5- to threefold as compared with values in infants not given protein supplements. However, the concentrations of methionine, tyrosine, phenylalanine, and lysine remained far below values considered harmful. The age at which maximal plasma amino acid concentrations in infants given human milk protein supplementation occur coincides with the age of the lowest serum albumin concentrations in infants fed only human milk. This suggests that high plasma amino acid concentrations may hasten albumin synthesis in very low-birth-weight infants.     

Low biotinidase activity in plasma of some preterm infants: possible source of false-positive screening results

Screening for biotinidase deficiency has been added recently to some national screening programmes. To clarify the problem of false-positive screening tests in premature infants, we have studied biotinidase activities in the plasma of this population in more detail. In 64 newborns (premature and term babies) biotinidase activities correlated positively with gestational age from the 2nd to the 30th day of life. During the 1st–3rd day the activities were below the normal adult range in all 64 infants. In 56 infants the activities subsequently increased gradually and reached the normal adult range during the 4th–40th day of life. In contrast, the biotinidase activities in eight preterm infants dropped during the 3rd–7th day of life. Impaired liver function as a possible cause for this finding could be ruled out in these infants. The lowest activities in these infants were measured during the 4th–6th day of life, i.e. unfortunately at a time when samples for the screening are normally taken. According to our data, 4–8 out of 48 preterm or small-for-date infants with biotinidase activities ranging from 4.7%–26% of the mean adult value would have given false-positive screening tests. A positive screening test was also obtained in a newborn and in an older unrelated child with a partial biotinidase deficiency. In these children the biotinidase activity did not rise but remained slightly below or at the lower range for heterozygotes (at 31% and 38% of the mean adult value). Currently we do not know whether such individuals are heterozygotes, or whether they have a variant of biotinidase deficiency. However, these children have developed normally without biotin therapy.Abbreviations DTT dithiothreitol     

Plasma amino acids in small preterm infants fed on human milk or formula.

Plasma amino acids were measured in 35 preterm infants, of whom 11 weighed less than 1000 g and 24 weighed between 1000 g and 1500 g at the time of sampling. Repeat samples were obtained in 18 at least seven days later. Seventeen infants were fed with preterm formula milk and 18 with expressed maternal breast milk at one to two hourly intervals during the study period. Formula fed infants gained weight faster than those fed on breast milk but there was little difference in amino acid patterns. Infants fed on breast milk were more likely to have concentrations of essential amino acids below the mid trimester fetal range than formula fed infants, but few infants in either feeding group had values above the fetal range. Those that did were equally distributed between both groups. Only two samples approached toxic concentrations, both in the group fed breast milk. The ratio of branched chain to aromatic amino acids was higher in the group fed on formula after correction for post conceptional age, implying that liver maturation may be accelerated by formula feeding. No correlations were found between plasma amino acid concentrations and nitrogen retention or metabolisable energy intake.     

Dietary protein source and plasma lipid profiles of infants

Total cholesterol and triglyceride concentrations were measured in plasma samples taken at 4 and 8 weeks of age from 40 full-term infants who had been fed either human milk or one of three formulas containing casein-to-whey ratios of 82:18, 66:34, or 50:50 to investigate whether dietary protein influenced the development of plasma lipid profiles. Infants fed the formula with the casein-to-whey ratio of 82:18 had significantly higher plasma cholesterol levels at both 4 and 8 weeks of age compared with other groups of infants (P less than .05). Infants fed the high-casein formula also showed an increase in plasma cholesterol levels with time (P less than .001). Plasma triglyceride concentrations decreased as concentration of casein decreased (P less than .05) among the formula-fed groups and increased with time. Infants fed human milk had plasma triglyceride concentrations similar to those infants who had been fed the 82:18 formula at 4 weeks of age; however, triglyceride concentrations eventually fell and were similar to those concentrations in infants who had been fed the 50:50 formula at 8 weeks of age. Results indicate that constituent lipids of human milk or formulas were not determining factors for changes observed in plasma cholesterol levels and triglyceride concentrations among groups. Since formulas differed only in proteins and their constituent amino acids, further investigation of the impact of dietary protein (amino acids) on development of blood lipid profiles in infants is warranted.     

Parenteral nutrition in preterm infants: influence of respiratory treatment and effect of different amino acid compositions

Thirty-three premature infants receiving parenteral nutrition during the first 5 days of life were divided into three groups. Infants in group I (n = 13) received no ventilatory therapy. Those in groups II (n = 10) and III (n = 10) were intubated and artificially ventilated because of hyaline membrane disease, apnea, or other illness. All infants received glucose, amino acids, fat emulsion, and electrolytes in their total parenteral nutrition regimen. Groups I and II were administered a transfer-adapted amino acid solution (Aminoplasmal paed 5%) for their protein supplementation, and group III, a so-called human milk-adapted solution (Aminoven?s 6%). The three groups were compared with respect to amino acid blood level, amino acid excretion, and nitrogen balance. Taurine levels decreased significantly during parenteral nutrition in all three groups. The other amino acids, with a few exceptions, remained within acceptable range. Elevations of serine, proline, and methionine were found in group III after the third day. All three groups exhibited good nitrogen retention. Excretion of amino acids was only about 1%.     

早期不同剂量氨基酸在早产儿静脉营养中的应用价值研究

目的 探讨应用不同剂量氨基酸在早产儿静脉营养中的近期疗效及耐受情况.方法 根据早期应用氨基酸剂量的不同,将2013 年3 月至2014 年6 月收治的生后24 h 内入院,出生体重1 000~2 000 g 的86 例早产儿随机分成低剂量组(n=29,每日1.0 g/kg,每天增加1.0 g/kg,最大达每日3.5 g/kg),中剂量组(n=28,每日2.0 g/kg,每天增加1.0 g/kg,最大达每日3.7 g/kg),高剂量组(n=29,每日3.0 g/kg,每天增加0.5~1.0 g/kg,最大达每日4.0 g/kg),同时进行常规的其他静脉营养及肠内营养支持.结果 早产儿最大体重下降程度随氨基酸输注量增加而降低,恢复出生体重天数、肠道营养达100 kcal/(kg · d)天数、住院时间及住院费用均随氨基酸输注量增加而减少,头围增长则随氨基酸输注量增加而增加(均P<0.05).高剂量组早产儿血尿素氮(BUN)水平在生后7 d 时高于中剂量组和低剂量组(均P<0.05);肌酐、pH 值、碳酸氢盐、胆红素及转氨酶水平在生后7 d,以及并发症发生率在各组间差异均无统计学意义(均P>0.05).结论 早产儿在生后24 h内静脉应用高剂量氨基酸可以改善早产儿生后近期营养状况,但有一过性BUN 升高.